Apparatus and method for cutting asphalt, concrete and other materials

ABSTRACT

An apparatus for dry cutting asphalt, concrete and other hard construction materials. The apparatus has a forward direction of operation and includes a circular saw, blade guard, and vacuum collection means. The circular saw includes a housing having front and back ends, a rotatable shaft extending from the housing, a blade fixed to the shaft, and means for rotating the shaft and blade in a direction that upcuts the material when the saw is conveyed in the forward direction. The blade guard is mounted to the housing. The blade guard includes a cover surrounding the upper portion of the blade, a shoe surrounding the lower portion of the blade, and an adjustable connection interface between the cover and the shoe. The vacuum collection means is connected to the blade guard.

This is a nonprovisional application claiming priority to provisional patent application No. ______, filed Oct. 28, 2005 by Douglas H. Walker et al. entitled Apparatus and Method for Cutting Road Surfaces.

FIELD OF THE INVENTION

The invention relates to an apparatus and method for dry cutting asphalt, concrete, masonry and other hard construction materials in all forms, wherein the dust generated during cutting is more effectively collected.

BACKGROUND OF THE INVENTION

During construction, maintenance, improvement, or renovation, it is often necessary to cut hard materials such as asphalt, concrete, mortar, ceramic, masonry, composite, and other construction materials. At many worksites, the slurry generated during wet cutting or the dust generated during dry cutting at many worksites must be collected and properly discarded. Road surfaces are one type of worksite at which dust cleaning and collection is required and, in fact, regulated by departments of transportation.

When concrete road surfaces are paved over with asphalt, the asphalt often cracks when the underlying concrete slabs heave and shift relative to one another. To prevent cracking, the asphalt is cut directly above and along each joint in the concrete. The cut is then filled with a flexible filler such as hot rubberized asphalt, silicon, or neoprene. The filler allows the underlying concrete slabs to heave without cracking the asphalt.

The asphalt is often cut with a powerful, four wheeled, walk-behind saw known as a flat saw. In the prior art, flat saw cutting of asphalt is performed wet by continuously injecting water into the blade guard. The slurry generated during cutting is ejected from the rear of the blade cover. When the slurry dries, a layer of road dust remains on the road surface, which is not only visually unappealing but is also a safety hazard. For example, when motor vehicles drive over the dust, it becomes airborne and obstructs visibility. To prevent accidents, the slurry must be cleaned from the road surface by a cleaning apparatus and/or work crew, which adds to the time and expense of the job.

To insure good adhesion to the asphalt, the groove must be cleaned prior to filling with the flexible filler. It is known in the prior art to trail the flat saw with a vacuum collection device. However, because of the depth of the groove and the properties of the slurry, known prior art vacuum cleaning devices do not adequately clean the groove. Alternatively, the groove may be cleaned with pressurized air or water, which doesn't collect the road dust. Therefore, a cleaning apparatus and/or work crew trailing the cutting crew is required in order to clean the groove and the road surface.

SUMMARY OF THE INVENTION

The invention comprises an apparatus for dry cutting asphalt and concrete in all forms including, for example, road surfaces, slabs, walkways, parking lots and decks, foundations, waterways, etc. The apparatus also cuts masonry, ceramic and other hard construction materials such as, for example, brick, mortar, stone, composite paver, tile, etc. The apparatus collects the dust created during cutting, and cleans the groove and area adjacent the groove.

The apparatus has a forward direction of operation and generally comprises a circular saw, a blade guard, and a vacuum collection means connected to the blade guard. The circular saw has a housing with front and back ends, and means for conveying the housing over the surface of the material. A rotatable shaft extends from the side of the housing and has a blade fixed thereto. The blade has an upper portion and a lower portion. A motor and transmission rotate the shaft and blade in a direction that upcuts the material when the saw is conveyed in the forward direction.

The blade guard is mounted to the housing and generally comprises a cover and a shoe. The cover portion surrounds the upper portion of the blade. The shoe surrounds the lower portion of the blade. The cover and shoe are connected by an adjustable connection interface. Vacuum collection means is connected to the blade guard. The height of the blade can be adjusted for different cut-depths.

The blade guard adjusts and surrounds the entire portion of the blade above the material surface at each cut-depth setting. In a preferred embodiment, the adjustable connection interface comprises a receptacle portion in the shoe and the cover telescopes within the receptacle portion.

In a preferred embodiment, the blade guard includes front and back ends, an air intake port in the back end, and a discharge port in the front end connected to the vacuum collection means. The discharge port has an internal opening proximate the projection point between the blade and the material surface. The internal opening is aligned directly in the trajectory of the dust from the projection point so that dust is projected directly into the exhaust port without contacting the interior of the blade guard. The exhaust port extends upwardly at an inclined angle relative to the trajectory of the dust from the projection point so that the dust impinges on the exhaust port at an angle less than 90 degrees.

The intake port has an internal opening aligned in the plane of the blade and above the groove, and located proximate the trailing contact point between the blade and the material surface. The air intake port may also have an air flow regulator.

The blade guard, the rotating blade, and the vacuum collection means create an air flow pattern flowing through the intake port, into the groove behind the trailing contact point of the blade and the groove, around the blade, and out the discharge port. The air flow pattern collects the dust, cleans the groove and adjacent surface, and cools the blade.

The apparatus has primary and secondary means for collecting the dust. With the primary means, dust is projected directly into the discharge port without contacting the interior of the blade guard and before the dust contacts the material surface. The air flow pattern helps direct the projected dust directly into the discharge port. With the secondary means, the air flow pattern dislodges dust from the trailing groove and directs it into the discharge port. The blade cover encloses the entire portion of the blade above the surface to contain the dust within an enclosed area.

The invention also provides a method dry cutting asphalt, concrete, ceramic, masonry, and other hard construction materials in all forms including, for example, road surfaces, slabs, walkways, parking lots and decks, foundations, waterways, etc. The apparatus collects the dust created during cutting, and cleans the groove and area adjacent the groove. In the novel method, the material is upcut with a circular saw. The portion of the blade above the material surface is enclosed to contain the dust within an enclosed area. The dust projected from the projection point between the blade and surface is collected before it contacts the surface. The trailing groove and adjacent surface are cleaned of any residual dust by directing a flow of air onto the groove and adjacent surface and vacuum collecting the residual dust.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a cutting device in accordance with an embodiment of the invention;

FIG. 2 is a side elevation of the blade guard of the cutting device in accordance with an embodiment of the invention;

FIG. 3 is a side elevation of the upper cover portion of the blade guard shown in FIG. 2 after the bottom shoe has been removed;

FIG. 4 is a top plan view of the blade guard of FIG. 2 after the bottom shoe has been removed and shown attached to the housing of the cutting device;

FIG. 5 is a side elevation of the upper cover portion of the blade guard of FIG. 3 after the outer plate has been removed;

FIG. 6 is a side elevation of the upper cover portion of the blade guard of FIG. 5 after the blade and blade flanges have been removed;

FIG. 7 is an opposite side elevation of the upper cover portion of the blade guard of FIG. 3;

FIGS. 8 a and 8 b are side elevations of the blade guard of FIG. 2 adjusted to cut grooves at two different depths;

FIG. 9 is a perspective view of the bottom shoe of the blade guard of FIG. 2; and,

FIG. 10 is a schematic view of the blade guard and method of cutting in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For the purpose of illustrating the invention, there is shown in the accompanying drawings a preferred embodiment of the invention wherein like reference numerals are used throughout to designate like elements. However, it should be understood by those of ordinary skill in the art that the invention is not limited to the precise arrangements and instrumentalities shown therein and described below.

The term “upcutting” shall mean the method of cutting wherein a saw having a circulating blade is moved across the surface of a material in a forward direction F1 and the blade 18 of the saw is rotated in a direction R1 that causes the teeth to cut upwardly from below the surface and causes the blade 18 to resist movement of the saw in the forward direction F1. The term “dust” shall mean the debris and dust created by cutting or scoring a material such as asphalt or concrete. The term “projection point” shall mean the point of contact P1 between the blade 18 and the surface 8 from which dust is projected outwardly from the blade 18 and upwardly from the road surface. The term “trailing contact point” shall mean the most rearward point of contact P2 between the blade 18 and the material in the bottom of the groove. The definitions are schematically illustrated in FIG. 10 with reference to cutting a groove 6 in a road surface 8.

The invention is illustrated and described below with reference to cutting an asphalt or concrete road surface 8. However, the invention may be used to cut and clean any form of asphalt or concrete material including, for example, slabs, walkways, parking lots and decks, foundations, waterways, roofs, etc. The invention may also be used to cut masonry, ceramic, and other hard construction materials including, for example, brick, mortar, stone, composite paver, etc.

An embodiment of the cutting device, designated generally by reference numeral 10, is schematically illustrated in FIG. 1. The device 10 is constructed to operate in the forward direction F1. The device 10 cuts grooves 6 of varying widths and depths in asphalt or concrete road surfaces 8 and simultaneously collects nearly all of the road dust generated during cutting.

The road surface cutting device 10 has a housing 12 with a front end 12 a, back end 12 b, and sides 12 c. A shaft 14, best seen in FIG. 4, extends from one side 12 c of the housing 12. One or more masonry blades 18 are mounted on the shaft 14. In a preferred embodiment, multiple blades 18 are stacked on the shaft 14 with the teeth locked in staggered radial locations relative to one another. The number of blades 18 selected by the operator will depend on the desired groove width.

A motor and transmission 20 drive the shaft 14. As shown by the direction arrows in FIGS. 1 and 10, the motor and transmission 20 rotate the shaft 14 in a direction R1 that creates upcutting by the blades 18 when the device 10 is conveyed in the forward direction of operation F1. The motor may be gas, electric, diesel or hydraulic.

The housing 12 is supported and conveyed over the road surface 8 by a front pair 16 a and back pair 16 b of wheels, which are mounted on shafts 22 a, 22 b, respectively. In the preferred embodiment, the back pair of wheels 16 b is driven by the motor to assist conveyance of the device 10 across the road surface 8.

In a preferred embodiment, the shaft 22 a of the front wheels 16 a extends from and retracts toward the housing 12 to raise or lower the front end 12 a of the housing 12 relative to the road surface 8. By raising or lowering the front end 12 a of the housing 12, the blade 18 is also raised or lowered relative to the road surface 8, thereby adjusting the groove depth without changing the diameter of the blade 18.

A blade guard 24 is removably attached to the housing 12. As best seen in FIGS. 8 a and 8 b, the blade guard 24 surrounds the shaft 14 and the upper portion of the blades 18 above the road surface 8 at a range of groove depths. The blade guard 24 has a front end 24 a and a back end 24 b, which are arranged in the same orientation as the front end 12 a and back end 12 b, respectively, of the housing 12. The blade guard 24 has an air intake port 26 at the back end 24 b and a discharge port 28 at the front end 24 a.

Referring to FIG. 2, the blade guard 24 generally has a two-piece construction comprising an upper cover 30 and a lower shoe 32. In a preferred embodiment, the cover 30 and shoe 32 have an adjustable, telescoping connection as best seen in FIGS. 8 a and 8 b.

Referring to FIG. 4, the cover 30 comprises an outer plate 34 and an inner plate 36, which form an internal cavity 38 within which the blades 18 rotate. The inner plate is arranged in between the housing 12 and the outer plate 34. The cover 30 surrounds the upper portion of the blade, which may include a substantial portion of the lower half of the blade 18. The shoe 32 surrounds the lower portion of the blade 18, which may include a portion of the upper half of the blade 18. The dimensions of the cover 30 and shoe 32 may vary so long as a range of overlap is provided.

Referring to FIGS. 3 and 4, the outer plate 34 is generally flat except for a protruding central hub portion 34 a. Referring to FIG. 3, the outer plate 34 has straight side edges 34 b and a straight bottom edge 34 c. The top edge 34 d has an arcuate shape. A plurality of fastener holes 35 are arranged around the periphery of the outer plate 34. Fasteners 46 extend through the holes 35 and connect the outer plate 34 to the inner plate 36.

Referring to FIGS. 4 and 5, the inner plate 36 has a pan-shaped cross-section. The central portion 36 a is generally flat and includes a central aperture (not shown) through which the saw shaft 14 extends into the internal cavity 38. Referring to FIG. 7, the side edges 36 b and bottom edge 36 c of the inner plate 36 are straight. The top edge 36 d is arcuate.

Sidewalls 40 are fixed to the side edges 36 b and top edge 36 d as best seen in FIG. 4. The sidewalls 40 extend transversely to the plane of the central portion 36 a. The sidewalls 40 define the depth of the internal cavity 38 and are preferably deep enough to accommodate a sufficient number of blades 18 to cut a groove about 2 in. wide.

A flange 42 is fixed to the arcuate upper sidewall 40. The flange 42 includes a plurality of holes 44 arranged around the periphery. Fasteners 46 extend through the holes and releasably connect the inner 36 and outer 34 plates. The inner plate 36 also includes threaded bores 48 proximate each bottom corner, which receive removable threaded fasteners 46 to connect the inner 36 and outer 34 plates.

Referring to FIGS. 4, 6 and 7, a mounting ear 50 is fixed to the upper portion of the exterior side of the inner plate 36. As best seen in FIG. 4, the ear 50 comprises a C-shaped channel segment having a web portion 50 a and a flange portion 50 b. To connect the ear 50 to the housing, a bolt 52 extends through a bracket 54 on the housing 12 and through the web portion 50 a. The flange portion 50 b is wide enough so that a nut 56 can be fit into the channel and easily tighten onto the bolt 52.

Referring to FIGS. 7, 8 a, and 8 b, a pair of shoe-hang brackets 58 are fixed to the upper portion of the exterior side of the inner plate 36. The shoe-hang brackets 58 extend lengthwise past the front 24 a and back 24 b ends of the blade guard 24. The free ends of the shoe-hang brackets 58 are connected to chains 60 from which the lower shoe 32 suspends when the blade guard 24 is not resting on the road surface 8. The shoe 32 can be removed by disconnecting the chains 60.

A flange bearing 62 is mounted by fasteners 63 to the central portion of the exterior side of the inner plate 36. The flange bearing 62 supports the blade guard 24 on the shaft 14 and provides an airtight seal between the shaft 14 and the inner plate 36. The seal improves the effectiveness of the vacuum collection means 88 and the air flow pattern described below.

The blades 18 are fixed to the blade shaft 14 by bolt 64 which tightens into an axial, threaded bore 66 in the shaft 14. The bolt tightens inner 68 and outer 69 blade flanges on opposed sides of the blade 18. Referring to FIG. 6, the inner blade flange 68 is keyed to the shaft 14.

Referring to FIG. 9, the shoe 32 has a rectangular-shaped receptacle portion 70 comprising parallel sidewalls 72, 74 and end walls 76, 78. The interior length and width of the receptacle 70 are slightly larger than the exterior length and width of the lower portion of the cover 30 so that the cover telescopes snugly into and forms a generally-airtight interface with the receptacle portion 70 of the shoe 32.

The bottom of the receptacle is formed by an abrasion-resistant skid plate 80, which includes a slit 82 through which the blades 18 extend. The slit 82 is slightly wider than the width of the maximum number of stacked blades 18. Except for the slit 82, the skid plate 80 seals the bottom of receptacle portion 70 of the shoe 32. Further, since the skid plate 80 lays flat on the road surface, the shoe 32 also surrounds and encloses the area surrounding the blade and cutting area, thereby containing the road dust within the blade guard 24. The enclosure formed by the shoe also improves the effectiveness of the vacuum collection means 88 and the air flow pattern described below.

Each end wall 76, 78 has a bracket 81 fixed to the exterior surface. The brackets 81 releasably connect to the chains 60 to prevent the shoe 32 from dropping off the cover when the shoe 32 is not resting on the road surface 8.

The air intake port 26 is formed in the back end wall 76 of the shoe 32. The air intake port 26 includes an adjustable valve 84, which regulates the amount of air drawn into the shoe 32.

The discharge port 28 is formed in the front end wall 78 of the shoe 32. The external end of the discharge port 28 is connected to a vacuum hose 28, which is connected to the vacuum collection means 88, which may be integrated with the housing or, as schematically illustrated in FIG. 1, remote from the cutting device 10. Referring to FIG. 10, an air flow pattern, shown by the single arrows, is created by the construction of the blade cover, the rotation of the blade and the vacuum of the collection means 88.

The internal opening of the intake port 26 is located in the plane of the blade 18 and groove 6, and proximate the trailing contact point P2. This location helps direct the air flow pattern down into the groove to dislodge and project any residual road dust into the discharge port 28.

The internal opening of the discharge port 28 is aligned to maximize the amount of road dust that is projected from the blade 18 directly into the discharge port 28. Depending on the depth of the groove, the angle at which road dust is projected from the blade, tangent to the projection point P1, will vary slightly as shown by the triple cluster of arrows in FIG. 10. Therefore, the internal opening of the discharge port 28 should be large enough to account for varying angles of projection.

In order to reduce friction, the discharge port 28 is inclined at an angle Θ from vertical to reduce the angle of impact of the road dust on the internal walls of the discharge port 28, preferably less than 90 degrees. For example, in the embodiment shown in FIG. 10, the discharge port 28 may be inclined at an angle Θ of about 25° from vertical.

In accordance with the method of the present invention, the road surface 8 is cut using a saw that traverses the road surface 8 in a forward direction F1 while simultaneously upcutting the road surface. During cutting, the area surrounding the blade 18 is enclosed to contain the road dust. The road dust within the containment area is then collected by primary and secondary methods.

In the primary method, the vast majority of road dust is collected proximate the projection point by locating a discharge port proximate the projection point and directly in the road dust trajectory. A vacuum is also applied the discharge port.

In the secondary method, any residual road dust that escapes the primary collection means and collects in the trailing groove 6 or on the adjacent road surface 8 is blown from the groove 6 by an air stream, and then withdrawn through discharge port 28. The air stream is created by locating an air intake port in the plane of the blade 18 and groove 6 proximate the trailing contact point P2. The rotation of the blade R1 and the vacuum applied to the discharge port 28 combine to create a strong, steady flow of air through the intake port 26, through the groove 6, around the blade 18, and out the discharge port 28, as schematically illustrated in FIG. 10. The steady flow of air has the added benefit of cooling the blade 18 during cutting.

By upcutting the road surface, road dust is projected upwardly out of the groove where it can more be more easily collected by the vacuum collection means. In contrast, if the blade were rotated in an opposite direction, i.e., “down cutting”, the road dust would be projected from the trailing contact point P2 into the trailing groove where it is far more difficult to remove and collect.

In one embodiment of the invention, the saw comprises a 72 hp. commercial diesel flat saw with an hydraulic system that raises and lowers the front end of the saw and hydraulics that propel the saw. The transmission is modified to rotate the blade in an upcutting direction. Operating the engine at 2,800 r.p.m. and the blade at 2,500 r.p.m. provides good results. The blade guard is connected to a HEPA type vacuum collection system which draws a vacuum of about 14 in. of lift. The diameter of the vacuum hose 86 reduces from 4 in. at the vacuum collection system 88 to 2 in. at the discharge port 28 of the blade guard 24.

While the principles of the invention have been described above in connection with specific embodiments, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention. For example, the blade guard 24 may be provided on a saw that is already constructed to upcut asphalt. The blade guard 24 is then mounted to the saw and used in accordance with the method described above. 

1. An apparatus for dry cutting materials, said apparatus having a forward direction of operation, comprising: a) a circular saw, including: i) a housing having front and back ends; ii) means for conveying said housing over the surface of the material; iii) rotatable shaft extending from said housing; iv) a blade fixed to said shaft, said blade having an upper portion and a lower portion; v) means for rotating said shaft and blade in a direction that upcuts the material when the saw is conveyed in the forward direction; b) a blade guard mounted to said housing, including: i) a cover surrounding the upper portion of said blade; ii) a shoe surrounding the lower portion of said blade; iii) an adjustable connection interface between said cover and said shoe; and, c) vacuum collection means connected to said blade guard.
 2. The apparatus recited in claim 1, including means for setting the blade at different cut depths.
 3. The apparatus recited in claim 2, wherein said blade guard adjusts and surrounds the entire portion of the blade above the material surface at each cut depth setting.
 4. The apparatus recited in claim 3, wherein said adjustable connection interface comprises a receptacle portion in said shoe and said cover telescopes within said receptacle portion.
 5. The apparatus recited in claim 1, said blade guard including front and back ends, an air intake port in said back end, and a discharge port in said front end connected to said vacuum collection means.
 6. The apparatus recited in claim 5, wherein said exhaust port has an internal opening proximate the projection point between said blade and the material road surface.
 7. The apparatus recited in claim 6, wherein said internal opening is aligned directly in the trajectory of the road dust from the projection point so that road dust is projected directly into said exhaust port without contacting the interior of said blade guard.
 8. The apparatus recited in claim 5, wherein said exhaust port extends upwardly at an inclined angle relative to the trajectory of the dust from the projection point so that the dust impinges on said exhaust port at an angle less than 90 degrees.
 9. The apparatus recited in claim 1, including an air flow regulator on said air intake port.
 10. The apparatus recited in claim 5, wherein said intake port has an internal opening aligned in the plane of the blade and above the groove, and located proximate the trailing contact point between the blade and the material surface.
 11. The apparatus recited in claim 5, wherein said blade guard creates an air flow pattern flowing through said intake port, into the groove behind the trailing contact point of the blade and the groove, around the blade, and out the discharge port.
 12. An apparatus for dry cutting a groove in road surfaces, comprising: a) a flat saw having a masonry blade, a forward direction of operation, means for rotating said shaft and blade in a direction that upcuts the road surface when the saw is conveyed in the forward direction, and means for setting the blade at different cut depths; b) an adjustable blade guard, having: i) front and back ends; ii) primary collecting means at the front end of the blade guard for collecting road dust before it contacts the road surface; iii) secondary collecting means at the back end of the blade guard for collecting road dust on the road surface and in the groove; iv) means for completely surrounding the portion of said blade above the road surface at each cut depth setting.
 13. The apparatus recited in claim 12, wherein said primary collecting means comprises a discharge port in the front end of the blade guard proximate the projection point between the blade and the road surface and a vacuum and collection means connected to said intake port of said blade.
 14. The apparatus recited in claim 13, wherein said discharge port is located directly in the trajectory of the road dust from the projection point between the blade and the road surface.
 15. The apparatus recited in claim 13, wherein said secondary collecting means comprises an intake port in the back end of the blade guard proximate the projection point between the blade and the road surface
 16. A method of dry cutting materials, comprising the steps of: a) providing a saw having a blade and a forward direction of operation; b) upcutting the material with the saw; c) collecting the dust created during cutting by applying a vacuum proximate the projection point between the blade and the material surface.
 17. The method recited in claim 16, including the step of enclosing the portion of the blade above the material surface.
 18. A method of dry cutting and cleaning a road surface, comprising the steps of: a) providing a saw having a road-surface blade and a forward direction of operation; b) upcutting the road surface with the saw; c) collecting road dust projected from the projection point between the blade and road surface before it contacts the road surface; d) cleaning the trailing groove and adjacent road surface of any residual road dust by directing a flow of air onto the groove and adjacent road surface and vacuum collecting the residual road dust.
 19. The method recited in claim 18, wherein road dust is collected proximate the projection point between the blade and the road surface.
 20. The method recited in claim 18, including the step of enclosing the area surrounding the blade and containing the road dust within the enclosed area.
 21. A blade guard for a flat saw having a forward direction of operation and a vacuum collection means, comprising: a) means for mounting said blade guard mounted to the saw: b) a cover surrounding the upper portion of the blade of the saw; c) a shoe surrounding the lower portion of the blade of the saw; d) an adjustable connection interface between said cover and said shoe; e) front and back ends; f) an air intake port in said back end; and, g) a discharge port in said front end connected to said vacuum collection means. 